Field of the Invention
The present invention relates to parts for bicycles and other cycles, particularly lightweight bicycles for recreational riding, racing, mountain biking and off-road uses. As is known, cycles are steered by handlebars which in turn are connected to a steering tube which extends upwardly from the front wheel fork of the cycle. The connecting part is known as a stem and the stem may also include a forwardly extending boom to position the cycle handlebar at a desired location forwardly of the stem tube for comfort of the rider. Not all stems include booms, however. Various cycle parts including stems are usually manufactured from tubular metals such as alloys of aluminum, magnesium or steel and of composite materials such as carbon fiber reinforced resin.
Since reduction of weight is of extreme importance in human-powered cycles, increasing use has been made of very light weight but strong composite tubular structures instead of aluminum, titanium and steel tubular parts of cycle frames and handlebars. Such composites are relatively easily damaged not only cosmetically but also structurally by surface nicks and gouges such as are often incurred by clamping. The need therefore exists for a stem having a handlebar clamp to which a cycle handlebar made of composite material can be readily attached and removed for re-positioning or replacement without damaging the handlebar.
In general, the larger the clamping surface area which contacts the handlebar, the less clamping stress is transmitted from the clamping surfaces of the clamp to the handlebar.